Aircraft flap system

ABSTRACT

In an aircraft, a lift-increasing flap system includes a flap carried on units which each comprise two guide members which are telescopic with one another, there being provided means such that on initial extension of the flap, the guides are coupled together and extend as one, but on further extension the guides are uncoupled such that one guide can extend from the other.

United States Patent [191 Lee Jan. 15, 1974 AIRCRAFT FLAP SYSTEM3,528,632 9/1970 Miles et al. 244 42 DA [75] In entor: Norman Lee, StAnnesfimsea 2,938,680 5/1960 Greene ct al. 244/42 Englarld FOREIGNPATENTS OR APPLICATIONS [73] Assignee: British Aircraft Corporation802,742 9/1936 France 244/42 DB Limited, London, England [22] Filed:Mar. 10, 1972 Primary ExaminerTrygve M. Blix Assistant Examiner-CharlesE. Frankfort [21] Appl' 233505 Att0mey-Cushman, Darby & Cushman [30]Foreign Application Priority Data Mar. 12, 1971 Great Britain 8236/71ABSTRACT [52] U 8 Cl 244/42 DA in an aircraft, a lift-increasing flapsystem includes a' [51] In. .Cl B6 3/54 flap carried on units which eachcomprise two guide 58] i D 42 DA members which are telescopic with oneanother, there being provided means such that on initial extension of244/42 42 42 44 the flap, the guides are coupled together and extend asone, but on further extension the guides are uncou- [56] uNlTE g s frizggs gz rENTs pled such that one guide can extend from the other.

2,405,726 8/1946 6 Claims, 7 Drawing Figures Zap 244/42 D 1 AIRCRAFTFLAP SYSTEM This invention relates to lift-increasing flap systems foraircraft.

According to the present invention, a lift-increasing flap systemincludes, in combination with an aircraft wing, 21 flap, an actuatordevice for extending and retracting the flap from and toward theaircraft wing, a first guide unit and means mounting the first guideunit for extension and retraction movement with respect to the wing, asecond guide unit, and means mounting the second guide unit forextension and retraction on the first guide unit, the second guide unitcarrying the liftincreasing flap, the guide unit's having releasablecoupling means whereby on initial'extension of the actuator the twoguide units are coupled together and move as one, but on furtherextension of the actuator the guide units can be extended from the firstguide unit.

Preferably the releasable coupling means includes a latch arm pivotablymounted on one of said guide units and a hook on the other of said guideunits, the aircraft wing having a cam surface positioned to causeengagement of the hook by the latch arm during initial extension of theactuator.

Preferably restraining means are provided to prevent thefirst guide unitfrotn further extension movement with respect to the wing on release ofthe releasable coupling means. The restraining means may be a furtherhook member mounted on the wing engageable by a further latch arm on thefirst guide unit.

A preferred embodiment of the invention is illustrated and describedwith reference to the accompanying drawings.

In these drawings:

FlG. l is a perspective view of-a flap system with the flap extended,

FIG. 2 is a side elevation of the flap system in a fully retractedposition; the wing and flap outlines are indicated in broken outline forclarity,

FIG. 3 is a side elevation similar to that of FIG. 2 but with the systemin a partly extended position,

FIG. 4 is a side elevation similar to those of FIGS. 2 and 3 but withthe system in a fully extended position,

FIG. Sis a section on line VV of FIG. 2,

FIG. 6 is a section on line VIVI of FIG. 2, and,

FIG. 7 is a section on line VII-VII of FIG. 2.

An aircraft has a wing l fitted with a lift-increasing flap 2 which isextendable from and retractable into the trailing edge region of thewing. In the fully retracted position (shown in FIG. 2) the flap 2conforms with the contour of the aerofoil section of the wing. The flap2 4 have pairs of rollers 5,6 and 7,8 respectively. The pair of rollers5,6, engage an outwardly facing channelshaped track 9 formed in a guideor track member 10. Similarly the pair of rollers 7,8, engage anoutwardly facing channel-shaped track 11 formed in aguide or On theirinwardly directed faces, the members 3 and track member 12. The tracks 9and 11 are of arcuate form. The track members and 12 are themselvesspaced apart, but are clamped one to the other to form a single unit 30(the first guide unit) by a series of bolts and spacers. These areindicated by the reference numeral 13 in their various positions.

The track members 10 and 12 each have on their,-

inner faces a pair of rollers 14, 15 and 16, 17, respectively. Thesepairs of rollers 14, 15 and 16, 17 respectively engage in outwardlyfacing channel-shaped arcuate tracks 18 and 19 formed on an a'rcuatetrack mem ber 20 (the second guide unit) which lies in between the trackmembers 10 and 12. The track members 10 and 12 have a further roller 21which is mounted on a spigot extending between the tracks and cooperateswith an upper face 22 of the track member 20.

The flap 2, comprising the main member 2a and the vane 2b, is carried bythe track memer 20. To achieve this, the track member 20 has adownwardly extending lug 23 and rearwardly extending spigot 24, the lug23 being engaged by a spigot 25 toward the leading edge of the flapmember 2a and the spigot 24 engaging a rear spar 26 of the flap member2a.

The mechanism is actuated by a screw jack, the nut 27 of which ismounted in the wing 1 and the screw 28 of which extends generallychordwise of the wing. This screw 28 is pivoted to the track member 20at 29.

The track members 10 and 12 (that is to say the unit 30) are releasablycoupled to the track member 20 by means of a latch arm 31 pivoted to theunit 30, the free end 32 of the latch arm 31 being engagable with a hook33 formed in that end of the track member 20 remote from the flap 2. Thefree end 32 of the latch arm 31 is further provided with a rollerfollower 34 which in the retracted and part-retracted positions of themechanism is caused to engage a cam track 35 formed on the wingstructure. Such engagement causes the free end 31 of the latch to engagethe hook 33.

The unit 30 has, adjacent the latch arm 31, a further latching device.This comprises a pivotable latch arm 36 whose free end 37 is adapted toengage with a hook 38 mounted on the wing structure. The latch arm 36has a crank member 39 which is contacted in certain conditions by a camformation 40 on that end of the screw 28 anchored to the track unit 30.The hook 38 is slotted at 41 so that the free end 37 of the latch arm 36can lie in the base of the slot and is then, together with the trackunit 30, prevented from moving in either chordwise direction i-.e.neither forwards or rearwards. This is shown in FIG. 3. Contact with thecrank member 39 by the cam formation 40 urges the latch arm 36 into afurther position in which the trackunit 30 can move only forwards i.e.into a retracted position.

The operation of the flap extension mechanism described is as follows:assuming the flap 2 and its actuating mechanism to be fully retractedinto the position indicated in FIG. 2, the flap 2 is extended byrearward movement of the screw 28. In this condition, the rollerfollower 34 is in engagement with the cam track 35 so that the latch arm31 engages the hook 33 and locks the trackunit 30 (i.e. track members 10and 12) to the track member 20. The assembly of items 30 and 20 thusmoves bodily rearward on rollers 5,6 and 7, 8 and tracks 9 and 11.

The cam formation 40 on the screw 28 is in contact with the crank 39during this initial movement so that the latch arm 26 is maintained insuch a position as to eventually engage the hook slot 41.

Extension of the screw 28 and rearward movement of the locked units 20and 30 continues until the position of FIG. 3 is reached. in thisposition the flap 2 is in a position of 12 droop, the 12 being measuredbetween the wing chord line shown at 42 and the flap chord line shown at43 (FIG. 3). Also in this position the roller follower 34 has justbecome disengaged from the cam track 35 thereby allowing the free end 32to drop away from the hook 33 so that further extension of the screw 28will separate the unit 30 and the track member 20.

The latch arm 36 has also engaged the hook 38 so that during the furtherextension of the screw 28 the unit 30 is in effect anchored to the wing.Thus the track member 20 is extended from the unit 30 on rollers 13, 15and 16, 17 and track 18, 19 and also as constrained by roller 21engaging with surface 22.

Further extension of the screw 28 moves the track member and hence theflap 2 to the fully extended position of FIG. 4. In this position theflap has a droop of 50, again measured between the wing chord line 42and the flap chord line 43. The cam formation 40 has now moved away fromthe crank member 29 and so the latching arm 36 has engaged the base ofthe hook slot 41. This feature ensures that on retraction of the flap,the unit 30 stays in the position of FIGS. 3 and 2 whilst the trackmember 20 is retracted into it.

Retraction of the flap is essentially in the opposite sequence to thatdescribed, namely, the track member 20 is drawn initially by theretracting screw 28 into the stationary unit 30 to the position of FIG.3.

The cam formation 40 then engages the crank member 39 and moves thelatch arm 36 to a position in which it can be freed from the hook 38 byforward movement of the unit 30. Such forward movement is caused by theengagement of the rollers 15, 17 with abutments at the ends of theirtracks on track member the flap actuating mechanism entirely within thewingcontour when retracted This is particularly important on variablesweep-back winged aircraft where any housings external to the wingsurface 'to cover any protruding mechanism require to present a minimumdrag producing shape to the airstream at varying positions of wingsweep. Such a shape is difficult to provide.

1 claim:

1. A lift-increasing flap system for aircraft which is arranged to bemovable from a fully retracted position to a position of intermediateextension and subsequently to a fully extended position including incombination with an aircraft wing, a flap, an actuator device forextending and retracting the flap from and toward the wing, a firstguide unit and means mounting the first guide unit for extension andretraction movement with respect to the wing, a second guide unit, andmeans mounting the first guide unit for extension and retractionmovement on the first guide unit, the second guide unit carrying theflap, the guide units having releasable coupling means whereby oninitial extension of the actuator the two guide units are coupledtogether and move as one until the said position of intermediateextension is reached, but, on further extension of the actuator, theyare uncoupled so that the second guide unit can be extended from thefirst guide unit to reach the said fully extended position.

2. A lift-increasing flap system according to claim 1 wherein the meansmounting the first guide unit for movement with respect to the wingincludes arcuate tracks engaged by rollers.

3. A lift-increasing flap system according to claim 1 wherein the meansfor mounting the second guide unit on the first guide unit also includesarcuate tracks engaged by rollers.

4. A lift-increasing flap system according to claim 1 wherein thereleasable coupling means includes a latch arm pivotably mounted on oneof the said guide units and a hook on the other of the said guide units,there being provided a cam surface on the wing positioned to causeengagement of the hook by the latch arm during initial extension of theactuator.

5. A lift-increasing flap system according to claim 1 whereinrestraining means are provided to prevent the first guide unit fromfurther extension movement with respect to the wing on release of thereleasable coupling means.

6. A lift-increasing flap system according to claim 5 in which therestraining means comprises a further hook member mounted on the wingengageable by a further latch arm on the first guide unit.

1. A lift-increasing flap system for aircraft which is arranged to bemovable from a fully retracted position to a position of intermediateextension and subsequently to a fully extended position including incombination with an aircraft wing, a flap, an actuator device forextending and retracting the flap from and toward the wing, a firstguide unit and means mounting the first guide unit for extension andretraction movement with respect to the wing, a second guide unit, andmeans mounting the first guide unit for extension and retractionmovement on the first guide unit, the second guide unit carrying theflap, the guide units having releasable coupling means whereby oninitial extension of the actuator the two guide units are coupledtogether and move as one until the said position of intermediateextension is reached, but, on further extension of the actuator, theyare uncoupled so that the second guide unit can be extended from thefirst guide unit to reach the said fully extended position.
 2. Alift-increasing flap system according to claim 1 wherein the meansmounting the first guide unit for movement with respect to the wingincludes arcuate tracks engaged by rollers.
 3. A lift-increasing flapsystem according to claim 1 wherein the means for mounting the secondguide unit on the first guide unit also includes arcuate tracks engagedby rollers.
 4. A lift-increasing flap system according to claim 1wherein the releasable coupling means includes a latch arm pivotablymounted on one of the said guide units and a hook on tHe other of thesaid guide units, there being provided a cam surface on the wingpositioned to cause engagement of the hook by the latch arm duringinitial extension of the actuator.
 5. A lift-increasing flap systemaccording to claim 1 wherein restraining means are provided to preventthe first guide unit from further extension movement with respect to thewing on release of the releasable coupling means.
 6. A lift-increasingflap system according to claim 5 in which the restraining meanscomprises a further hook member mounted on the wing engageable by afurther latch arm on the first guide unit.